atos-genesys: do not use threads (#29320)

As threads were hiding errors from asynchronous requests, we now still
hide errors when cache is full, but log them.

passerelle/apps/atos_genesys/models.py

@@ -97,7 +97,8 @@ class Resource(BaseResource, HTTPResource):
         cache = utils.RowLockedCache(
             function=self.call_select_codifications,
             row=self,
-            key_prefix='atos-genesys-codifications')
+            key_prefix='atos-genesys-codifications',
+            logger=self.logger)
         return cache()
 
     @endpoint(name='codifications',
@@ -274,7 +275,8 @@ class Resource(BaseResource, HTTPResource):
             cache = utils.RowLockedCache(
                 function=self.call_select_usager,
                 row=link,
-                key_prefix='atos-genesys-usager')
+                key_prefix='atos-genesys-usager',
+                logger=self.logger)
             dossier = cache(link.id_per)
             # build text as "id_per - prenom - no
             text_parts = [str(link.id_per), '-']

passerelle/apps/atos_genesys/utils.py

@@ -1,11 +1,12 @@
 import time
 import six
-import threading
 from contextlib import contextmanager
 
 from django.db import transaction
 from django.core.cache import cache
 
+from passerelle.utils.jsonresponse import APIError
+
 DEFAULT_DURATION = 5 * 60  # 5 minutes
 
 # keep data in cache for 1 day, i.e. we can answer a request from cache for 1 day
@@ -29,11 +30,12 @@ class RowLockedCache(object):
        a thread, prevent multiple update using row locks on database models and
        an update cache key.
     '''
-    def __init__(self, function, row=None, duration=DEFAULT_DURATION, key_prefix=None):
+    def __init__(self, function, logger=None, row=None, duration=DEFAULT_DURATION, key_prefix=None):
         self.function = function
         self.row = row
         self.duration = duration
         self.key_prefix = key_prefix or function.__name__
+        self.logger = logger
 
     def _key(self, *args, **kwargs):
         keys = []
@@ -59,17 +61,12 @@ class RowLockedCache(object):
                     cacheline = cache.get(key)
                     if now - timestamp < self.duration:
                         return cacheline['value']
-                    updatekey = 'update-' + key
-                    update = cache.get(updatekey)
-                    if not update or (update['timestamp'] - now >= self.duration):
-                        cache.set(updatekey, {'timestamp': now}, CACHE_DURATION)
-
-                        def update():
-                            value = self.function(*args, **kwargs)
-                            cache.set(key, {'value': value, 'timestamp': now}, CACHE_DURATION)
-                            cache.delete(updatekey)
-
-                        threading.Thread(target=update).start()
+                    try:
+                        value = self.function(*args, **kwargs)
+                        cache.set(key, {'value': value, 'timestamp': now}, CACHE_DURATION)
+                    except APIError as e:
+                        if self.logger:
+                            self.logger.error('failure to update cache %s', e)
             return cacheline['value']
         else:
             value = self.function(*args, **kwargs)

tests/test_atos_genesys.py

@@ -215,7 +215,7 @@ def test_row_locked_cache(genesys, freezer):
         assert rlc() == 1
         assert f.calls == 1
 
-    # Check that cache update only launch one thread and f() is called only once again
+    # Check that with cache update f() is called only once again
     freezer.move_to('2018-01-01 00:02:00')
     F.value = 2
     counter = 0